Marine plywood

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b_arrington

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I need to rebuild an upholstered bench on my boat. Anyone have a local source for marine plywood? Preferably near Port Jeff area.

Current bench structure is made from what looks like Starlite XL that was built up in layers on the edge. It wasn't nearly strong enough for a family boat, even with careful use.
 
Save yourself some money and buy exterior plywood. Coat it with resin and call it a day.
 
I wouldn't use wood at if you could help it. I'd use something like PBC board.
 
I had my seats re-done a few years ago, and the wood that was used previous to me doing this looked just like regular plywood with a layer of fibreglass on it...
 
The original frame was cellular PVC and its just not strong enough. I'm going to reuse the vinyl skin a d cushion so the dimensions have to be the same - ca t be thicker cellular PVC. My reason for wanting marine plywood is that it has more plys for a thickness to give more strength, has fewer voids, and the glue is usually rated better.

I can't really glass it because the upholstery has to get stapled to the base. I will coat it in some polyurethane though.
 
Brad:
exterior grade ply has waterproof glue like marine. Any X grace such as CDX. the only difference today is all voids are filled in marine. Home depot sold marins in the past.

IMO any grade ply needs to be throughly sealed especially the edges when used out in the open.
 
No matter how well sealed your core material is, the holes the staples make will allow a pathway for moisture into the plywood. Unless you need structural strength, marine plywood in this application is over kill. This is a bench seat, not a hull section, use the exterior grade plywood. You will have to change/update the upholstery in a few years anyway. Save your money to spend on Monel staples.
 
If you want marine plywood, Roberts Plywood in Deer Park is the place to go. They have just about any kind of sheet good you could possibly want. They also stock a pretty good supply of dimensional lumber.
 
L. Keith hit the nail on the head...or should I say staple.

One thing you may want to do is seal the plywood under the upholstery and leave it raw/un-sealed on the exposed. That way it can dry out. You can paint the exposed surface with Copper Green which is an anti fungal but will still allow drying.
 
Why not pressure treated plywood? That's what I used when I re-upholstered my coaming bolsters.
 
Saint James Lumber in Saint James may have it, give them a call.

Walter
 
Thanks for all the ideas, both for materials and suppliers. I was planning on using stainless staples; I see the point on monel as stainless will still corrode without oxygen.

I was shying away from pressure treated plywood. In my experience it tends to be more warped than non PT, and the have less plys than other types (less strength). I would also be concerned about the PT chemicals corroding the staples very quickly.
 
Stay away from pressure treated lumber. The jury is still out on the safety of the water run-off. Exterior grade is fine.
 
Mike,
Was your PT plywood brown? Some years back I was looking up Boric Acid as an ant killer. They said they would start using it instead of the green stuff in PT lumber. That was about the time PT lumber started coming coated in Brown stuff. I didn't check to see if the brown stuff was Boric Acid.
 
I found marine-grade plywood at my local lumber yard (Thurbur Lumber). It was AB grade, made of fir.

I did check Home Depot first for suitable exterior grade, but the 1/2 they stocked was only 3-plies. That was rather bendy and I wanted more plies for greater strength. The pressure treated plywood at HD was very wavy and also 3-plies, so that was out.

Over the weekend I templated out the new bench from the old broken one, cut the sections and got it partially assembled. I make a modification so need to test-fit it on the boat. The marine plywood seems very sturdy compared to the original Starlite XL materials.
 
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